class Rectangle{
  num width=0,height=0;
  num get area => width*height;
  set area(value){
    width=value/height;
  }
}

void main(){
  var rect = new Rectangle();
  rect.height=20;
  rect.width=10;
  print(rect.area);
  rect.area=100;
  print(rect.width);
}
